package ${filePackageName};

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import java.security.Key;
import java.security.SecureRandom;
import java.util.Base64;

/**
 * DES是一种对称加密算法，所谓对称加密算法:加密和解密使用相同的秘钥的算法
 * @author ${projectAuthor}
 * @version 1.0
 * @date ${nowDate}
 */
public class DESUtil {

	public static Key key;

	private String secretKey;

	private static DESUtil desUtil = null;

	private static String CHARSETNAME="UTF-8";
	private static String ALGORITHM="DES";

	private Logger logger = LoggerFactory.getLogger(DESUtil.class);

	public static DESUtil getInstance(String secretKey){
		if(desUtil==null){
			desUtil = new DESUtil(secretKey);
		}else {
			if(!secretKey.equals(desUtil.secretKey)){
				desUtil = new DESUtil(secretKey);
			}
		}
		return desUtil;
	}

	private DESUtil(String secretKey){
		try{
			//生成DES算法对象
			KeyGenerator generator=KeyGenerator.getInstance(ALGORITHM);
			//运用SHA1安全策略
			SecureRandom secureRandom=SecureRandom.getInstance("SHA1PRNG");
			//设置上密钥种子
			secureRandom.setSeed(secretKey.getBytes());
			//初始化基于SHA1的算法对象
			generator.init(secureRandom);
			//生成密钥对象
			key=generator.generateKey();
			this.secretKey = secretKey;
			generator=null;
		}catch(Exception e){
			//e.printStackTrace();
			logger.error("DESUtil error",e.getMessage());
		}
	}

	/**
	 * 获取加密的信息
	 * @param str
	 * @return
	 */
	public String encrypt(String str){
		//基于BASE64编码，接收byte[]并转换成String
		try {
			// 按UTF8编码
			byte[] bytes = str.getBytes(CHARSETNAME);
			// 获取加密对象
			Cipher cipher = Cipher.getInstance(ALGORITHM);
			// 初始化密码信息
			cipher.init(Cipher.ENCRYPT_MODE, key);
			// 加密
			byte[] doFinal = cipher.doFinal(bytes);
			// byte[]to encode好的String并返回
			return Base64.getEncoder().encodeToString(doFinal);
		} catch (Exception e) {
			//e.printStackTrace();
			logger.error("DESUtil error",e.getMessage());
		}
		return null;
	}
	
	/**
	 * 获取解密之后的信息
	 * 
	 * @param str
	 * @return
	 */
	public String decrypt(String str) {
		// 基于BASE64编码，接收byte[]并转换成String
		try {
			// 将字符串decode成byte[]
			byte[] bytes = Base64.getDecoder().decode(str);
			// 获取解密对象
			Cipher cipher = Cipher.getInstance(ALGORITHM);
			// 初始化解密信息
			cipher.init(Cipher.DECRYPT_MODE, key);
			// 解密
			byte[] doFinal = cipher.doFinal(bytes);
			// 返回解密之后的信息
			return new String(doFinal, CHARSETNAME);
		} catch (Exception e) {
			//e.printStackTrace();
			logger.error("DESUtil error",e.getMessage());
		}
		return null;
	}
	
	public static void main(String[] args) {
		//加密
		String encrypt = DESUtil.getInstance("000000").encrypt("123456");
		System.out.println(encrypt);

		String decrypt = DESUtil.getInstance("000000").decrypt(encrypt);
		System.out.println(decrypt);
	}
}